With the new form region feature in Outlook 2007, developers have a powerful new way to customize the Outlook UI. The four types of form regions—Separate, Adjacent, Replacement, and Replace-All—provide a wide variety of UI options. In this chapter, you saw how form regions can be created to customize Inspector windows as well as the reading pane. You also learned about custom message classes, as they are required for using the Replacement and Replace-All form region types.
VSTO supports two form technologies to create form regions with: Windows Forms and Outlook Forms. You saw how Outlook Forms can be created and imported into Visual Studio and how the controls are accessed from managed code. You also dived deeper into the programming model to discover additional ways to customize form regions.
Also in this chapter you saw a simple way in which form regions integrate with the Ribbon: They automatically add a button to switch to the form region page, for example.
In the next chapter, you see how VSTO supports creating a wider range of Ribbon customizations.